A level is necessary for a practitioner employed in civil engineering and building, electrical and plumbing engineering, or interior decorating when measuring the angle of a datum plane. Among various kinds of levels, a level with a bubble vial is the most popular with the practitioner.
As shown in FIGS. 1-2, a level (1) is disclosed in Taiwan Utility Model Patent NO. M436831, which comprises a body (10) and at least one vial (20) mounted in the body. The body has a first side edge (101) and a second side edge (102), and the first side edge has at least one receiving portion (12) mounted with a magnetic element (13) therein to be magnetically placed on a surface containing iron. When the vial is installed in the body, the vial is inserted into the body through a first hole (161) so that two sides of the vial are mounted in the first hole and a second hole (162) respectively. And then, the first hole is filled with a layer of melted glue (19) to fix the vial in a hole (16). Finally, a screwdriver is used to tread an end plug (18) into the first hole so as to limit the vial in the hole by the obstruction caused by the end plus without coming off.
As further shown in FIGS. 3-5, a level tool (100) is present in U.S. Pat. No. 7,946,045, which includes a top wall (116) and a bottom wall (118). The top wall is mounted with multiple passageways (134) for accommodating vials (112), and the bottom wall is mounted with multiple holes (148) for accommodating magnetic inserts (146). After the vials are mounted in the passageways, plugs (140a, 140b, and 140c) are inserted into the passageways to allow the vials to be fixed in the passageways.
In addition to the foregoing ways that the plug (18 or 140) is inserted into the first hole (161) or the passageways (134), another traditional way is that silicone, wax, or glue is used to seal the first hole (161) or the passageways so as to fix the vial.
All above ways, including the plug insertion and the glue sealing, can lead to not only a rise in the manufacture cost, but also a bad appearance. In these ways, multiple slots are formed by drilling in various angles, and then multiple plugs each having a shape corresponding to each slots are produced. For example, the three plugs (140a, 140b, and 140c) in U.S. Pat. No. 7,946,045 are produced to match the holes with different shapes. As for glue sealing, besides the adhesive, i.e. silicone, wax, or glue, after calibrating the vial, a fast-acting adhesive is used to place the vial, and then the hole is filled with silicone or hot cement. In the above processes, the adhesion strength between the different materials should be considered, the used amount of the adhesive should be controlled, and the glue surface should be flat and beautiful. Therefore, the manufacture cost rises.